Production of vanillin and i-vanillin



I Patented June 30, 1931 UNITED f STATES PATENT orrica rnmnmon nonnncxna, ornnnrm-nnnnm GERMANY, assxenon To mm mm: J. n. mom. mmnozsrnscmr, or nmLm-m'rz, emm

Application fled November 6, 1928, Serial No.

This invention relates to the production of vanillin and i-vanillin.

' When heating safrol with alcoholic caustic alkali or an alcoholic solution of alkali alcoholate to temperatures of about 140170 0., the methylene ether group is broken up and an adjunction of the alcohol employed I takes place, the allyl radical being simultaneously transformed. l0

Solrol (i-Batrol) Hitherto it was believed that the above mentioned transformation of safrol to i-safrol and the simultaneous splittin of i-safrol only leads to propenylor th ihydroxybenzene-mono-alkoxy-methyl-ther, in which the hydroxyl group being in the metaposition to the propenyl radical carries the alkoxy-meth-yl radical. In fact, however, it has been ascertained that the reaction product forms a mixture containing the alkoxymethyl radical as well in the metaas in the para-position to the propenyl group. It is therefore possible to obtain from safrol, va-

liters of a 25% methylalcoholic caustic potwater.

146,850, and in Germany November 10, 1925.

ash solution for 20 hours in an autoclave provided with a stirrer to '13014 0 G. Then the methyl alcohol is distilled off and the residue isdissolved in 4 liters of water; For removing the undecomposed safrol .the aqueous solution is extracted by shakin it' with benzene. After distilling ofi' the nzene about. 30 grams of i-safrol remain from the benzene solution.

' Potassium salts of Pro nyl-dlhydroxybenuno-monomethoxyme hylothers (1) (LB; (l H O,CH, CH,OH KOH 0 H, (3 H, OCH OOHQOK H O To the aqueous alkaline solution, 700 grams of conc. hydrochloric acid are-added to neutralize the excess of alkali, and then 800 grams of dimethyl sulfate are introduced un der stirring, the tem rature-not exceeding C. The methyl et er deposits in the form of an oil upon the reaction product; itmay be separated by siphoning and washed with Dlmoth 1- Pro 11 l-dih dro benzene I to Y Y Y mot methyl-methyl other;

' ,When-distilled in vacuo it goes over as a colorless oil at 160163 C. and 13 millimeters. The output amounts to 900 grams. From the aqueous alkalinesolution about grams of the non-methylated product may be recovered by acidulating. 900 grams of the methyl ether are-refluxed for 6 hours with 5.5 liters of alcohol, 2-6 liters of watenand 4 cubic centimeters of hydrochloric acid. Then the alcohol is distilled off, the residue is dissolved in diluted caustic soda solution and the latter is extracted by shaking it with benzene for removing the non-saponified methyl ether.

From the benzene solution about 20 grams of non-saponified methyl ether may again be recovered. a

The alkaline solution is acidified and the precipitated phenols are collected by means of benzene, washed with water and dried.

After the benzene is distilled 05, 650

rams of a product remain consisting of a mlxture of i-chavibetol and i-eugenol.

from 142 to 146 0.; it consists mainly of l-eugenol.

100 grams of this product are heated to i-Eugenol or i-Ohavibetol about C. with 230 cubic centimeters of 12% caustic soda solution. The sodium salt which crystallizes after cooling down is filtered ofl and washed with common salt (4) C H- C H OH OCH 03 a a HO OH OOH CH CO H i-Eugenol or i-Ohavibetol Now it is possible to treat this mixture of i-eugenol and i-chavibetol in such a manner that it is almost completely transformed to the more valuable i-eugenol or vanillin respectively. At first the i-chavibetol having the higher fusing point is separated by freezing-out and then it is transformed to propenyl veratrol by treating it with methylating means, as with dimethyl sulfate or methyl chloride or other halogenide 620. By heating the propenyl veratrol with alkali at tem-' It has been found that the alkali salts of i-" eugenol are difiicultly soluble in water, alco hol &c. contrary to those of i-chavibetol. It is therefore possible to separate, from a solution containing the above mentioned phenols besides, to all appearance, further isomers, after freezing-out the main quantity of the i-chavibetol, the i-eugenol in the form of an alkali metal salt. The i-eugenol separated therefrom by acidifying is obtained with a degree of pureness not yet described; whereas hitherto i-eugenol was only known to solidify in the cold, the product obtained according to the present inventionshows a fusing point of 24 C.

208 grams of the mixture of i-chavibetol and i-eugenol obtained according to 'the above example are mixed with 130 grams of rexahydrotoluol. After standing in the cold for some hours the crystallized product is filtered off and Washed with some hexahydrotoluol. 7 9 grams are obtained having a fusing point of 94 C. The mother liquor is freed from its solvent and on distilling in vacuo 120 grams of a product are obtained which at a pressure of 13 millimeters, boils at crystalline product.

Vanillin and i-Vanillin olution. In this manner grams of sodium 1-eugenolate are obtained. By decomposlng the same with diluted acid pure i-eugenol showing a fusing point of 24 C. is

obtained.

The waste alkali metal salt solution from the separation of the i-eugenol yields on acidulating an oil corresponding to about 20% of the i eugenol and i-chavibetol consumed. I have not succeeded in separating therefrom, even by means of the above described method, the two propenyl-dihydroxybenzene ethers, after freezing-out the remainders of i-chavibetol which might be present. However I have surprisingly attained the desired end by methylating the present mixture of phenols and splitting up the completely methylated reaction product with an alkali at a somewhat elevated temperature. From the mixture thus produced as well i-chavibetol as i-eugenol may be obtained. Again an oil is produced in a quantity amounting to 20% of the raw material uncapable of yielding a It may be treated in the above described manner preferably in connection with a fresh batch, for recovering the two isomers. It is, however, not necessary to start from the oil itself, but when methylating with dimethyl sulfate, for instance, one may start directly from the liquor remaining from the separation of the sodium i-eugenolate.

After separating the i-chavibetol and the i-eugenol from 100 grams of a mixture con taining both isomers according to the above example, a salt solution corresponding to about 20 grams of the starting material is left. To this solution 16 grams of dimethyl sulfate are added by drops. The temperature rises to about 35 C. the reaction product being deposited as an oil upon ,the aqueous solution. By distilling the separated end washed product propenyl dihydroxybenzenc dimethyl ether in the form of a slightly yellow-colored oil is obtained, showing a fusing point of from 142 to 146 C. at a pressure of 13 millimeters.

grams of this dimethyl ether, .90 grams of caustic alkali,and'9() grams of alcohol are heated to 140 C. in an autoclave provided residue distills in vacuo at from 145 to the with a stin'ing device for about 20 hours. The alcohol is then distilled ofi, the residue is dissolved in water, and the aqueous solution is washed with ether for-removing the dimethyLether which might have escaped the splitting action. The 'solution is carefully acidulated and the separated oil is dissolved in ether. After distllling ofi' theether the 152 C. under a pressure of 13 millimeters. The output amounts to about 80 grams. From the distillate i-chavibetol crystallizes out on cooling down. The massis allowed to stand at about 0 C., and then the i-chavibetol the quantity of which amounts to about 25 grams, is filtered by suction. To the filtrate a 15% causticsoda solution is added, and after some standing the crystallized sodium i eugenolate isfiltered by suction.- By suspending in water and acidfying free i-eugenol is obtained from the sodium salt,- lts' quantity amounting to about 40 grams. The vrelmainder of the product of the-splittingreaction left in the'motheriliquor is precipitated by acidulating and is-then returned into process. p

The whole of the i-chavibetol isnow transformed, in the well-known manner, to i-eugenol methyl ether by boiling with a methyl halogenide in alcoholic solution. 'With theoretical output products boiling at,.150-151 C. under a pressure of 14 millimeters are ob:

ethers with an acid, removing from the re suiting mixture of the propanyl orthodihydroxybenzene-monomethyl ethersthe i-chavibetol by freezing out, converting the remain- 1 ing more soluble propenyl-orthodih droxIybenzene monoethers into their alka imetal salts, thereby removing from them the less soluble alkali metal salt of the i-eugenol, decomposing the said salt by an acid, and oxidizing the resulting i-eugenol to vanillin.

- 2. rocess of v producmg vanillin, comprising treating 1-2-dihydroxybenzene methylene ether substituted-in the 4-.position by an lunivalent unbranched alkylene radical C 115 at elevated temperatures. with alcoholic al- ,kali, methylating the reaction product heatingjthe resulting mixture of methyl-alkoxy methyl ethers with an acid,-removi'ng from .the resulting mixture of the propenyl-orthodihydroxybenzene-Inonomethyl ethers the i-chavibetol by freezing out, converting the remaining more soluble propenyl-orthodihytained. v v v droxybenzene-monoethers into their alkali (5) drama-011( -OOH. 4 ,'C.H.-0.H. 00H. i-Chavlbetol Propenyl-veratrol heated to 140 with a stirring device together with 80 parts of alcohol and 80 parts of powdered caustic potash for about 20 hours (aqueous or alcoholic caustic alkali may likewlse be used for.

carrying out the reaction) OH-CHOK(3) am ammooflaf 3 5 I ropenyl-veratrol c H C H OK (4) :Hereupon the alcohol isdistilled oil, the residue is dissolved in water and the aqueous solution is extracted by shaking the same with benzene. Now-the solution is acidulated, the precipitating oil is dissolved in benzene, washed with water and dried over Na SO,.. After distilling off the benzene a partially crystalline, partially oily substance remains which is separated by freezing-out-and, if required, by adding benzene to pure i-chavi-" betol and a liquid part mainly consisting of i-eugenol. From the last-mentioned filtrate i-eugenol is obtained in the above described manner.

The propenyl dihydroxybenzene monomethyl ether obtained as described is transformed in the well-known manner, for inmethylating the remaining mixture of propeny -ortho-dihydroxybenzene -monomethylethers, heating with alcoholic alkali, acidulating, again returning the remaimng mix- OCH (4) time into the process, and oxidizing-the i-eugenol to vanillin.

3. Process of producing vanillin, comprising treating 1-2-dihydroxyben'zene methy- Potassium salt 0! l-Chavibetol Potassium salt of l-Eugenol lene ether substituted in the 4-position by an:

uni'valent unbranched alkylene radical H at. elevated temperatures with alcoholic alkali, methylating the reaction product heating the resulting mixture of methyl-alkoxymethyl ethers with an acid, removing from the resulting mixture of: the propenyl-orthodihydroxybenzene-monomethyl ethers the i-chavibetol by freezing out, converting the propenyl-orthodihydroxybenzene monoethers into their alkali metal salts, thereby l'emoving from them the lesssoluble alkali lneta1 salt of the i-eu genol, and decomposing the said salt by an acid, methylating the remaining mixture of propenyl-orthodihydroxybenzene-monomethyl ethers and the said ichavibetol, heating with alcoholic alkali, acidulating, again returning the remaining mixture into the process, and oxidizing the i-eugenol to vanillin.

4. A process for the purpose described, characterized by subjecting a mixture containing isoeugenol and isochavibetol to crysstallization by means of cooling, whereby the isochavibetol is converted into crystalline form, and thereafter separating the liquid isoeugenol from the crystalline isochavibetol.

5. A process for the purpose described, characterized by subjecting a mixture of alkyloxy isoeugenol and alkyloxy isochavibetol to methylation and hydrolysis so as to obtain a mixture of isoeugenol and isochavibetol, subjecting the said resulting mixture to crystallization by means of cooling, whereby the isochavibetol is converted into crystalline form. and thereafter separating the isoeugenol from the isochavibetol.

6. A process for the purpose described, characterized by heating safrol with alcohol caustic potash to a temperature sufficient to )roduce alkoxy-methoxy-hydroxy-propenylenzenes, methylating the mixture of phenols so produced. hydrolyzing the methylated product, thereby obtaining a mixture of iso cugenol and isochavibetol, subjecting the said mixture to crystallization by means of cooling, whereby the isochavibetol is converted into crystalline form, and separating the isoeugenol as a liquid from the crystalline isochavibetol.

7. The steps in the process of making isomeric alkyl substituted phenol derivatives from safrol which consist in heating safrol with caustic alkali and a primary aliphatic alcohol to a temperature of between 140- 170 C., acidifying the reaction product to obtain said derivatives as two isomeric phenol ethers, and alkylating said phenol ethers.

8. The steps in the process of making isomeric alkyl substituted phenol derivatives from safrol which consist in heating safrol with caustic alkali and a primary aliphatic alcohol to a temperature of between 140 to 170 (3., acidifying the reaction product to obtain said derivatives as two isomeric phenol ethers, and alkylating said phenol ethers with a dialkylsulphate.

9. The process of making isomeric alkyl substituted phenol derivatives from safrol which consists in heating safrol with caustic alkali and a primary aliphatic alcohol to a temperature of between 140 to 170 (1.,

acidifying the reaction product to obtain said derivatives as two isomeric phenol ethers, and treating said isomeric phenol ethers to convert the hydroxy groups to alkoxy groups and the alkoxymethoxy groups tohydroxy groups.

alkali and a primary'aliphatic alcohol to a temperature of between 140 to 170 (1.;

acidifying the reaction product to obtain said derivatives as two isomeric phenol ethers, and treating said isomeric phenol others to convert in successive steps the hydroxy groups to alkoxy groups and the alkoxymethoxy groups to hydroxy groups.

s a new composition of matter, an equimolecular mixture of two isomeric phenol ethers having the formulae 4-alkoxymethoxy-3-alkoxy-l-propenylbenzenes and 4-alkoXy-3-alkoxymethoxy-1-propenylbenzenes.

12. The process of obtaining a mixture of isoeugenol and its isomer isochavibetol from safrol which consists in heatin safrol with caustic alkali and a primary a iphatic alcohol to a temperature of 140 to 170 C., acidifying the reaction product and treating the resulting mixture of isomeric phenol ethers so as to convert the hydroxy groups to methoxy groups and the alkoxymethoxy groups to hydroxy groups. a

13. The process of obtaining a mixture of isoeugenol and its isomer isochavibetol from safrol, which consists inheating safrol with caustic alkali and a primary aliphatic alcohol to a temperature of 140 to 170 C., aciditying the reaction product and treating the resultingmixture of isomeric phenol ethers so as to convert in successive steps the hydroxy groups to methoxy groups and the alkoxymethoxy groups to hydroxy groups.

14. The process of obtaining a mixture of isoeugenol and its isomer isochavibetol from sa-frol, which consists in heating safrol with caustic alkali and a primary aliphatic alcohol to a temperature of 140 to 170 (3., acidifying the reaction product, methylating the isomeric reaction product obtained and heating the resulting product with a weak acid solution.

15. The process of obtaining a mixture of isoeugenol and its isomer isochavibetol from safrol, which consists in heating safrol with caustic alkali and a primary aliphatic alcohol to a temperature of 140to170C., acidifying the reaction product, methylating the isomeric reaction product obtained and heat ing the resulting product with a weak acid in alcoholic solution.

16. The process of obtaining a. mixture of isoeugenol and its isomer isochavibetol from safrol, which consists in heating safrol with caustic alkali and a primary aliphatic alcohol to a temperature of 140 to 170 C., acidifying the reaction product, treating the isomeric reaction product obtained with dimethyl-sulphate in the presence of caustic alkali to convert the hydroxy groups into methoxy groups and then heating the resulting product with a weak acid solution to convert the alkoxymethoxy groups to hydroxy groups. I

17. A new composition of matter consisting of a mixture of isoeugenol and isochavibetol in molecular proportion.

18. In the process of making isomeric a1- kyl substituted phenol derivativesfrom safrol, which consists in heating safrol with caustic alkali and a to a temperature 0 between 1&0" to 170? 0., acidifying the reaction product to obtain said derivatives as two isomeric phenol ethers,

and alkylating said'phenol others, the stepwhich conslsts in heating the mixture of isomeric alkylated phenol ethers with a weak acid solutlon.

In testimony whereof I afiix m si nature; FRIEDRIOH BOEDdEC rimary aliphatic alcohol. 

